1. Field of the Invention
The present invention relates to an image-forming device, such as an inkjet printer, having an optical sensor for detecting ink cartridges mounted in the device, as well as the existence of ink in the ink cartridges.
2. Description of the Related Art
Conventional inkjet printers used as image-forming devices, such as facsimile devices, photocopying devices, and the like, are provided with an optical sensor for optically detecting whether an ink cartridge is mounted in the device and whether the cartridge contains ink. This optical sensor includes a light-emitting element for radiating a light toward an ink cartridge, which is formed of an optically transparent material, and a light-receiving element for sensing the amount of light reflected by or permeated through the ink cartridge. Since the amount of light reaching the light-receiving element changes according to the existence of ink and the existence of an ink cartridge, the optical sensor can sense the existence of ink or an ink cartridge by detecting the amount of received light.
Sometimes a light different from expected one is reflected from the irradiated surface of the ink cartridge or the like, due to the condition of the irradiated surface. Such a light consists a noise signal, thereby degrading the detecting precision. For this reason, the inventors of the present invention attempted to reduce the noise signal by orienting the optical sensor to radiate light onto the surface of the ink cartridge in a non-perpendicular direction, specifically at an inclination angle of about 10 degrees.
However, it is difficult to slant the optical sensor at the prescribed angle in relation to the irradiation surface of the ink cartridge. If there is an error in the mounting angle of the optical sensor, the relative positioning of the optical sensor and the irradiation surface of the ink cartridge will be different from the intended setting. As a result, the optical sensor cannot detect the light or a portion of the light that is reflected from the ink cartridge at the intended detecting position and cannot, therefore, accurately detect the existence of ink or of a mounted ink cartridge.
Further, due to irregularities in its sensitivity, the optical sensor may not achieve precise detection when the intensity of irradiated light from the light-emitting element is uniform. In order to overcome such a problems, a process has been conventionally conducted to calibrate the intensity of the light irradiated from the light-emitting element. In this process, an ink cartridge is filled with sufficient ink, and the intensity of the light is calibrated so as to achieve a predetermined amount of light received by the optical sensor. This calibrating process is conducted for each printer by controlling the drive of the light-emitting element through pulse-width modulation.
However, because the amount of light reflected from the ink cartridge differs according to the color of ink stored in the cartridge, the calibration process must be conducted for each ink cartridge in a printer provided with a plurality of ink cartridges containing different color ink. This leads to an increase in complexity and duration of the calibration process.
Another conceivable method for overcoming the above problem due to irregularities in sensitivity of the optical sensor is to measure an amount of light reflected from a single ink cartridge and to estimate the amount of reflected light for other ink cartridges based on the measured value. However, it is difficult to estimate appropriate calibration values for other ink cartridges using this method, because the amount of light reflected from the ink cartridge varies according to the color of ink contained therein. Hence, while it is possible to detect with high accuracy the amount of ink remaining in the ink cartridge for which reflected light has been actually measured, it is not possible to measure with accuracy the amount of ink remaining in ink cartridges using the estimated value.
Further, in order to detect the existence of ink optically, it is necessary to move the ink cartridge to a position near the optical sensor, and it requires a certain time interval to move the ink cartridge to such a position and to perform the detection using the optical sensor with respect to the ink cartridge at the position. Because recording operation cannot be performed during this time interval, detecting the existence of ink during the recording operation reduces the processing speed of the recording device.
There has been developed an ink cartridge for practical use that is provided with a plurality of prisms on the irradiated surface of light irradiation. These prisms are integrally formed on the surface of the ink cartridge in a shape that repeatedly alternates in peaks and valleys, which form a plurality of reflecting surfaces. This configuration enables to detect with accuracy the amount of ink remaining in the ink cartridge using the properties of the prisms of reflecting and penetrating light.
However, since this conventional device is configured with only a single optical sensor to detect the existence of ink in a plurality of ink cartridges, the carriage supporting the ink cartridges must be continually moved while the optical sensor is irradiating a light onto each ink cartridge to detect the existence of ink therein. Since the amount of reflected light varies depending on whether it is reflected from a valley or a peak in the prisms or therebetween, the waveform read by the optical sensor has a zigzag shape. Accordingly, it is not always possible to detect the existence of ink with accuracy at some reading points.
In view of the foregoing, it is an object of the present invention to provide an image-forming device capable of detecting with accuracy the existence of ink cartridges mounted in the device and the existence of ink contained in the ink cartridges using optical sensors.
It is another object of the present invention to provide an image-forming device having a simple construction and capable of reliably calibrating the intensity of light irradiated from the optical ink sensor to detect with accuracy the existence of ink and ink cartridge.
It is another object of the present invention to provide an image-forming device capable of detecting the existence of ink without slowing the processing speed of the image-forming device.
It is another object of the present invention to provide an image-forming device employing prisms to form alternate peaks and valleys on the ink cartridge and capable of accurately detecting the existence of ink cartridges and of ink inside the ink cartridges while the ink cartridges are moving.
In order to achieve the above and other objects, according to the present invention, there is provided an image forming device including a cartridge, a carriage, a sensor, a memory, and a first detection unit. The cartridge contains an ink and has a surface. The carriage mounts the cartridge thereon and reciprocally moves along with the cartridge. The sensor detects an amount of a reflected light reflected from the cartridge. The sensor includes a light emitting unit and a light receiving unit. The light emitting unit irradiates a light onto the surface of the cartridge in a non-perpendicular direction with respect to the surface while the carriage is moving along with the cartridge. The light receiving unit receives the reflected light. The amount of the reflected light changes depending on the amount of ink contained in the cartridge and further on existence and non-existence of the cartridge on the carriage. The memory stores a first threshold value and a second threshold value differing from the first threshold value. The first detecting unit compares the amount of received light and the first threshold value for detecting an ink-near empty condition of the cartridge and compares the amount of received light and the second threshold value for detecting whether or not the cartridge is mounted on the carriage.
There is also provided an image forming device including at least one cartridge, a sensor, a carriage, a control unit, and a detecting unit. The at least one cartridge contains an ink and has an irradiated portion. The sensor that detects an amount of reflected light reflected from the irradiated portion of the cartridge. The sensor includes a light emitting unit that irradiates a light onto the cartridge at the irradiated portion and a light receiving unit that receives the reflected light. The carriage mounts the cartridge thereon and reciprocally moves along with the cartridge. The control unit controls an intensity of the light irradiated from the light emitting unit. The detecting unit moves the carriage to a predetermined position where the light irradiated from the light emitting unit is irradiated on the cartridge at the irradiated portion and detects an amount of the ink contained in the cartridge based on the amount of reflected light detected by the sensor. The detecting unit detects existence of the ink in the cartridge when a level of the ink containing in the cartridge is above the irradiated portion. The control unit controls the intensity of the light such that the detecting unit detects the existence of the ink when the level of the ink is above the irradiated portion of the cartridge based on the amount of reflected light reflected from the irradiated portion of the cartridge that contains a brightest-color ink. With this configuration, accurate detection of the existence of the ink cartridge and the ink in the ink cartridge is achieved.
By using the brightest ink cartridge to adjust the amount of light emitted from the light-emitting element, accurate detection can be achieved even when the sensitivity of the ink sensor is irregular. Further, by performing such adjustments using the ink cartridge with the brightest ink, suitable detection can be reliably performed on ink cartridges containing other inks that are less bright. Therefore, a single adjustment value can be applied to all ink cartridges when multiple colors of ink are used, thereby simplifying the process and reducing the processing time.
Further, there is provided an image forming device including a cartridge, a sensor, a transport means, and a detecting unit. The cartridge contains an ink. The carriage mounts the cartridge thereon and reciprocally moves along with the cartridge. The sensor detects an amount of reflected light reflected from the cartridge. The sensor includes a light emitting unit that irradiates a light onto the cartridge and a light receiving unit that receives the reflected light. The transport means transports a recording medium in relation to a printing operation. The detecting unit controls, during a recording-medium transporting period, the carriage to move to a position where the light irradiated from the light emitting unit is irradiated onto the cartridge and detects an amount of the ink contained in the cartridge based on the amount of reflected light detected by the sensor.
With this configuration, because the detecting unit detects the amount of the ink contained in the cartridge during the paper-feed interval, there is no need to put printing operations on standby, thereby improving processing speed of the image forming device.
There is also provided an image forming device including a cartridge, a carriage, a sensor, a detection unit, and a reading unit. The cartridge contains an ink and has an irradiated portion. The carriage mounts the cartridge thereon and moves along with the cartridge. The sensor detects an amount of reflected light reflected from the irradiated portion of the cartridge. The sensor includes a light emitting unit that irradiates a light onto the cartridge at the irradiated portion and a light receiving unit that receives the reflected light. The detection unit detects an amount of the ink contained in the cartridge based on the amount of the reflected light detected by the sensor. The irradiated portion of the cartridge is provided with prisms in a shape that repeatedly alternates in peaks and valleys. Adjacent two of the valleys are separated by a predetermined first interval. The reading unit controls the carriage to move to a predetermined position where the light irradiated from the light emitting unit is irradiated onto the cartridge and reads levels of reflected light from a waveform for the amount of reflected light at a second interval non-integral multiples of the first interval, based on which the reading unit detecting an amount of the ink contained in the cartridge.
In this configuration, because the second interval is non-integral multiples of the first interval, the reading unit can read the waveform at portions corresponding to portions of the prism other than the valleys. Accordingly, the existence of the ink and of the ink cartridge can be detected with accuracy.
There is also provided an image forming device including a cartridge, a carriage, a sensor, a first memory, a detecting unit, a measuring unit, an error, a second memory, and a calibrating unit. The cartridge contains an ink and has a surface. The carriage mounts the cartridge thereon and reciprocally moves along with the cartridge. The sensor detects an amount of a reflected light reflected from the cartridge. The sensor includes a light emitting unit and a light receiving unit. The light emitting unit irradiates a light onto the surface of the cartridge in a non-perpendicular direction with respect to the surface while the carriage is moving along with the cartridge. The light receiving unit receives the reflected light. The amount of the reflected light changes depending on the amount of ink contained in the cartridge. The first memory stores a threshold value. The detecting unit compares the amount of received light and the threshold value for detecting an ink-near empty condition of the cartridge. The measuring unit measures a detect position of the cartridge based on the amount of reflected light detected by the sensor. The error detection unit detects an error amount between the detect position and a predetermined theoretical position. The second memory stores the error amount. The calibrating unit calibrates a detection position for detecting the ink-near empty condition.